1. Field of the Invention
The present invention relates to methods and systems for processing samples using microfluidic systems. More particularly, the invention relates to moving fluid samples within a microfluidic system. Description of the Related Art
2. Background
Microfluidic devices are typically formed of substrates (made of silicon, glass, ceramic, plastic and/or quartz) which include a network of micro-channels through which fluid flows under the control of a propulsion mechanism. The micro channels typically have at least one dimension which is on the order of nanometers to hundreds of microns.
Microfluidic devices process minute amounts of fluid sample to determine the physical and chemical properties of the sample. Microfluidic devices offer several advantages over a traditional macro-scale instrumentation. For example, in general, they require substantially smaller fluid samples, use far less reagent, and process these fluids at substantially greater speeds than macro-scale equipment.
Electric fields are used as a propulsion mechanism for some microfluidic devices. In such devices, a high voltage, on the order of kilovolts, is applied across electrodes within the device to thereby generate an electric field in the micro channels. The field imposes a force on ions within the fluid, thereby propelling the ions through the micro channel. The fluid itself may also be propelled by the motion of ions moving within the fluid.
Gas pressure is also used to propel fluid through micro channels. In some devices, a source of pressurized gas, external to the microfluidic device, is connected to the microfluidic device to supply a gas pressure, which propels the fluid. Gas pressure may also be generated by a heated chamber within the microfluidic device itself to propagate fluid within a micro channel.